Gene-environment interaction

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Gene-environment interaction is a term used to describe any phenotypic effects that are due to interactions between the environment and genes. Naive nature versus nurture debates assume that variation in a given trait is primarily due to either genes, or the individual's experiences. The current scientific view is that neither genetics nor environment are solely responsible for producing individual variation, and that virtually all traits show gene-environment interaction. The specific pattern that relates the average expression of trait across a range of environments is known as a genotype's norm of reaction.

In some combinations of environments and genotypic ranges, heritability can be 100% even while group differences are completely environmental. For heritability to be 100%, random variation in expression must not occur.
In some combinations of environments and genotypic ranges, heritability can be 100% even while group differences are completely environmental. For heritability to be 100%, random variation in expression must not occur.

A classic example of gene-environment interaction is Tryon's (1942) artificial selection experiment on maze-running ability in rats. Tryon produced a remarkable difference in maze running ability in two selected lines after seven generations of selecting "bright" and "dull" lines by breeding the best and worst maze running rats with others of similar abilities. The difference between these lines was clearly genetic since offspring of the two lines, raised under identical typical lab conditions, performed too differently. This difference disappeared in a single generation, if those rats were raised in an enriched environment (Cooper & Zubek 1958) with more objects to explore and more social interaction. This result shows that maze running ability is the product of a gene-by-environment interaction, the genetic effect is only seen under some environmental conditions.

[edit] References

  • Cooper, R. M. & Zubek, J. P. (1958). Effects of enriched and restricted early environments on the learning ability of bright and dull rats. Canadian Journal of Psychology, 12:159–164.
  • Tryon, R. C (1940). Genetic differences in maze-learning ability in rats. Yearbook of the National Society for the Study of Education 39:111-119.
  • Tryon, R. C. (1942). Individual differences. in F. A. Moss (ed) Comparative psychology (Rev. Ed.). Prentice-Hall: NY.

[edit] See also

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The development of phenotype
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Genetic architecture
Non-genetic influences
Developmental architecture
Evolution of genetic systems
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List of evolutionary biology topics